Dibasic silver salts of alkenyl sucicinic acids and method for combating fungus infestations therewith



Patented Oct. 13, 1953 DIBASIC SILVER SALTS OF ALKENYL SUC- CINIC ACIDSAND METHOD FOR COMBAT- ING FUNGUS INFESTATIONS THEREWITH Mearl A.

Kise, Portsmouth, Va., assignor to Allied Chemical & Dye Corporation,

New York, N. Y.,

a corporation of New York N Drawing. Application December 1, 1949,Serial No. 130,601

8 Claims. (01. 167-22) This invention relates to new fungicidalcompositions, to a method for preparing them and to a method forcombating fungus infestations therewith.

In the past it has been the practice to control plant-infesting fungi bythe application of sulfur-containing, copper-containing and otherchemical fungicides.

An outstanding disadvantage in the use of chemical fungicides employedin the past has been that many such fungicides, when used in quantitiesor concentrations sufiiciently high, efiectively to control theparticular fungus infestation, caused serious injury to the plant host.

It has long been known that silver in the form ofits inorganic saltssuch as silver nitrate, possesses outstanding germicidal and fungicidalproperties.

However, silver salts have not heretofore been considered useful asfungicides since silver salts in general. e. g., silver nitrate, areknown to be severely toxic to plants and hence not ractical asfungicides.

It is an object of the present invention to provide new fungicidalcompositions containing sil ver wherein the active ingredients haveunusually high fungicidal activity at acceptably low phytotoxicitylevels.

This and other objects are accomplished according to my invention whichprovides new compositions wherein the dibasic silver salts of alkenylsuccinic acids having from 4 to 24 carbon atoms in the alkenyl groupcomprise the major active toxicants, and a method for combating fungi byapplying such compositions to the host.

The dibasic silver salts of alkenyl succinic acids of the presentinvention may be represented by the formula to 24 carbon atomsinclusive. The alkenyl group may contain straight or branched chains.

The silver salts above described may be prepared from the correspondingalkenyl succinic acid anhydride through the corresponding Watersolubledibasic alkali metal salts according to the following reactions whereinR is an alkenyl group containing from 4 o R-CH-COONa R--CHCOOAg 2N8,Hr-C O O No (as water- Hz-C 0 0 Ag soluble salt) Alkenyl succinic acidanhydrides suitable for preparation of the dibasic silver salts employedin the compositions and method of the invention may be obtained'asdescribed in U. S. Patent No. 2,411,215 of Mearl A. Kise and Robert F.Engle entitled Production of Substituted Succinic Anhydrides, by thereaction of maleic anhydride and a cracked distillate fractioncontaining aliphatic mono-olefins.

The dibasic silver salts of alkenyl succinic acids prepared from theacid anhydrides derived from cracked petroleum distillates, as describedin the patent above referred to, are mixtures corresponding in alkenylchain length to the chain length of the compounds present in the olefinsof the distillate fraction. Such fractions or cuts may be takencontaining the desired predominant number of carbon atoms in the chains,cuts containing predominantly 06-8, and Clo-l2 carbon atoms beingpreferred, and any of the cuts, or mixtures of the whole range or partsthereof, of compounds containing from 4 to 24 carbon atoms inclusive aresatisfactory.

The dibasic silver salts of alkenyl succinic acids may be prepared byany suitable process, for example according to the above reactions. Incarrying out the preparation, the dibasic alkali metal salt of thedesired alkenyl succinic acid may be dissolved in water, or the aqueousreaction mass in which the dibasic alkali metal salt is formed may beused as such. To this solution there is added, with stirring and whileprotecting the mixture from exposure to light, a sufiicient quantity ofa water-soluble silver salt, such as AgNOa in water solution, todisplace the alkali metal of the dibasic alkali metal succinic acid withsilver. A creamy, light gray mixture results which may be furtherdiluted and stirred vigorously for an hour to insure completion of thedisplacement reaction. The dibasic silver salt of the alkenyl succinicacid thus produced is a solid at normal room temperatures. and may beisolated and freed from impurities, e. g., sodium nitrate, etc., bymechanical separation such as filtration, centrifugation or the like,and washing with water to eliminate water-soluble impurities. The silversalt may then be dried and powdered.

The dibasic silver salts of alkenyl succinic acids of the typecontemplated herein are new compositions of matter. They are white,crystalline solids, only slightly soluble in water, and are relativelyinsoluble in acetone and benzene, and vary in molecular Weights fromabout 386 for salt of alkenyl These salts tend to exhibit a slightdarkening.

on exposure'to light, which does not materially afiect their fungicidalcharacteristics if not unduly prolonged. When stored in brown glasscontainers or in other manner so as to exclude substantial amounts oflight, the salts are sufficiently stable for commercial requirements,usually exhibiting no appreciable deterioration on storage over periodsof at least a year. The dibasic silver salt of a single alkenyl succinicacid may be used in the fungicidal compostions of my invention or amixture of such salts may be employed as brought out above. Particularlysuitable mixtures are those in which the alkenyl groups containpredominantly 6-8 carbon atoms and 10-12 carbon atoms respectively.Examples showing typical procedures for the preparation of the silversalts of alkenyl succinic acids are set forth below (parts are byweight) Example 1 Fifty-four parts of an alkenyl succinic acid anhydridein which the alkenyl group consisted chiefly of C1042 radicals washeated to ISO-4.0v C. and 15.8 parts of sodium hydroxide in the form ofa 2.11 normal aqueous solution was added thereto over a 10 minuteperiod. The mixture was heated at 100 C. with stirring for 1.8 hours,then cooled to 25 C. The solution was protected from light and 70.72parts of AgNOs in 250 parts of water were added with stirring over aminute period. The creamy, light gray mixture which resulted was dilutedwith 200 parts of water and stirred vigorously for one hour. The mixturewas then filtered and washed with distilled water until washings were(N03) -free, with precautions taken to protect from light. The dampfilter cake was dried at low pressure over CaClz, powdered and bottled.The yield was 92.76 parts, equivalent to about 92.8% of theoretical. Thematerial analyzed 41.97% silver compared to 42.75% theoretical.

Example 2 491 grams (2.5 mols) Ce-a alkenyl succinic acid anhydridehaving a neutral equivalent of 98.2 was cooled to l0-l5 C. and 2500 ml.of 2 N sodium hydroxide was added slowly. The mixture was heated at 85C. with stirring for 1 hour. The solution was neutralized with 0.25 NH2804 and added with stirring to 892 grams of AgNOz dissolved in 2500ml. of water. The silver salt precipitated. The mixture was protectedfrom light, and after one hour standing was filtered and product washedwith liters of distilled water. The damp filter cake was dried at 55 C.at low pressure. Yield: 900 g.; analysis 50.43% Ag; theory 50.39% Ag.Calculated average molecular weight 428.2.

The new silver salts of my invention exert outstandingly toxic ellectsagainst a number of fungus organisms heretofore difficult to control. Aswill appear from the tabulated data hereinafter set forth, this activityis evident at unusually low concentration levels such that danger to theplant is not a hazard, even at concentration levels sufiicient to insurecomplete control of the organisms. Thus, effective fungicidal protectionis afforded against early potato blight (Alternaria solani) when appliedat the rate of one-eighth pound of salt per 100 gallons of spray;against black rot of sweet potatoes (Ceratostomella fimbriata) by theuse of water suspensions containing as little as 0.025% of the silversalt when used as a sprout dip; against brown rot (Sclerotiniafructz'cola) of fruit trees and against apple scab (Venturia) both thelatter-at concentration of less than one part per million of solution.Virtually complete salts in compositions containing a major proportionof a diluent or carrier material of low or negligible phytotoxicity,either as dusts. or as liquid sprays 'or dips. In the preparation ofliquid compositions, water may conveniently be used since it is a cheapand effective diluent and carrier, and readily disperses the silversalts or my invention. Other well-known spray amendments may be used inmy compositions such as wetting, sticking and spreading agents and thelike, and other antiparasitic materials may be added, for example, tocontrol pests other than fungi.

Fungicidal and phytocidal tests were carried out using the particulardibasic silver salts of alkenyl sucoinic acids of my invention indicatedin the tables below, and with the results there set forth.

In Table I are recorded the LB-50 values (i. e., the doses required toeffect 50% controlof the fungus) obtained as results of a series oftests against the organisms Sclerotim'a Jructicola, AZ- ternario solaniand Venturia in which successively decreasingconcentrations of a dibasicsilver salt of a C1042 alkenyl succinic acid were used in tests againstspores of the organisms mentioned above to determine the minimumconcentration of silver salt in parts per million in water necessary toprevent 50% of the spores from germinating. The results are given inTable I below:

TABLE I LD-50 value of the dibasic silver salts of 010-12 alkenylsuccinic acid in parts per million in water spray As is well known,fungicides having an LD-50 value below about 1,000 parts per millionconcentration are considered to be of value as fungicides. It isaccordingly apparent that the silver salts of my invention areoutstandingly toxic against various fungus organisms.

In order to indicate the non-toxic nature of the new fungicides towardthe host at effective concentration levels, phytotoxi'city tests ontomato plants, one of the most sensitive of cultivated plants, resultsof which are recorded in Table II below, were carried out and indicatethat no injury to the plant takes place by the application thereto ofsuspensions of my new silver salts at concentrations greatly in excessof the amount required for control of early and late tomato blight. Itwill be observed that no injury was apparent at a dosage of 04%, i. e.400 parts per million silver salt concentration and severe injury wasnot inflicted until the dosage reached 0.2%, i. e. 2,000 parts permillion,

6 conditions and with the results indicated in Table IV below:

TABLE IV Potato blight control Rate of application, lb./l00 gals.Percent tubers Yield Fungicidal composition Parts T t 1 showing bushels0 a visible per acre mixture DDT other plight None... None... None 11. 8180 }2lb llb do as 250 }'41b. .do 31b 6.0 330 1 basic Gas 04 1361b". d0.0.125lb.Agselt 8.8 297 Dibasic Ag salt of 010- alkenyl succinic acid.

whereas less than a single part per million concentration aifordseffective (LD-SO) fungus control.

TABLE II Phytotoxz'city of dibasic silver salts of 010-12 alkenylsuccinic acids on tomatoes Black rot of sweet potatoes is readilycontrolled by low concentrations of the dibasic silver salts of myinvention as indicated by tests carried out in Louisiana, results ofwhich are reported in Table III below. In these tests, discs preparedfrom roots of the Puerto Rico variety of sweet potato were inocculatedby spraying with a spore suspension of black rot fungus. Afterwards theinocculated discs were treated at the concentrations and for the periodsof treatment listed below with a fungicidal dust prepared by mixing ofthe dibasic silver salt of a 06-8 alkenyl succinic acid with 75% clay,and suspending this dust in water in the concentrations indicated.Results, both as to fungus control and phytotoxicity, are given in TableIII below:

TABLE In Control of potato blight is effected by application of thedibasic silver salts of alkenyl succinic acid to the host as indicatedin Table IV below. In carrying out these tests in New Hampshire fields,the test mixtures were made up with a standard quantity ofdichlorodiphenyltrichloroethane (DDT) to control insects at the sametime, and the crop was given five separate applications by spraying thepotato plant foliage under the From the above data, it will be apparentthat the yield was increased 32% by the standard copper fungicidewhereas the silver salt used at ,5 the concentration (metal basis) gavean increase of 19%.

I claim:

1. As new compositions of matter, the dibasic silver salts of alkenylsuccinic acids having the general formula wherein R is an alkenyl groupcontaining from 4 to 24 carbon atoms inclusive.

2. As new compositions of matter adapted for use as fungicides, mixturescomprising dibasic silver salts of alkenyl succinic acids having thewherein R represents in the several components or the mixture at leasttwo diiferent alkenyl groups selected from alkenyl groups containingfrom 4 to 24 carbon atoms inclusive.

3. As a new composition of matter adapted for use as a fungicide. amixture of dibasic silver salts of alkenyl succinic acids having thefollowing general formula wherein R represents a plurality of alkenylgroups containing predominantly 6-8 carbon atoms.

4. As a new composition of matter adapted for use as a fungicide, amixture of dibasic silver salts of alkenyl succinic acids having thefollowing general formula wherein R represents a plurality of alkenylgroups containing predominantly 10-12 carbon atoms.

5. A method for combating fungus infestations on plants which comprisessubjecting them to the action of a composition containing as theessential active toxicant a compound having the general formula whereinR. represents an al'kenyl group containing from 4 to 24 carbon atomsinclusive.

6. A method for combating fungus infestations on plants which comprisessubjecting them to the action of a composition containing as theessential active toxicant a mixture of compounds having the generalformula wherein R represents a plurality of alkenyl groups containingpredominantly 6-8 carbons atoms.

7. A method for combating fungus infestations on plants which comprises.subjecting them to the action of a composition containing as theessential active toxicant a mixture of compounds having the generalformula 8 wherein R represents a plurality of alkenyl groups containingpredominantly 10-12 carbon atoms.

8. A process for combating fungoidblight of potato plant which comprisesapplying to the leaf surfaces of the potato plant an aqueous dispersionof the dibasic silver salt of an alkenyl succinic acid containing from 4to 24 carbon atoms, inclusive, in the alkenyl group.

MEARL A. KISE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,853,397 Banks Apr. 12, 1932 2,360,426 Kyrides Oct. 17, 19442,380,699 Kyrides July 31, 1945 2,381,852 Hochwalt Au 7, 1945 OTHERREFERENCES

1. AS NEW COMPOSITIONS OF MATTER, THE DIBASIC SILVER SALTS OF ALKENYLSUCCINIC ACIDS HAVING THE GENERAL FORMULA
 5. A METHOD FOR COMBATINGFUNGUS INFESTATIONS ON PLANTS WHICH COMPRISES SUBJECTING THEM TO THEACTION OF A COMPOSITION CONTAINING AS THE ESSENTIAL ACTIVE TOXICANT ACOMPOUND HAVING THE GENERAL FROMULA